Dihydropyrimidine Dehydrogenase Levels Research Articles

Inhibition of HSD17B13 protects against liver fibrosis by inhibition of pyrimidine catabolism in nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, in which prognosis is determined by liver fibrosis. A common variant in hydroxysteroid 17-beta dehydrogenase 13 (HSD17B13, rs72613567-A) is associated with a reduced risk of fibrosis in NAFLD, but the underlying mechanism(s) remains unclear. We investigated the effects of this variant in the human liver and in Hsd17b13 knockdown in mice by using a state-of-the-art metabolomics approach. We demonstrate that protection against liver fibrosis conferred by the HSD17B13 rs72613567-A variant in humans and by the Hsd17b13 knockdown in mice is associated with decreased pyrimidine catabolism at the level of dihydropyrimidine dehydrogenase. Furthermore, we show that hepatic pyrimidines are depleted in two distinct mouse models of NAFLD and that inhibition of pyrimidine catabolism by gimeracil phenocopies the HSD17B13-induced protection against liver fibrosis. Our data suggest pyrimidine catabolism as a therapeutic target against the development of liver fibrosis in NAFLD.

Role of Genetic Polymorphisms in Drug-Metabolizing Enzyme-Mediated Toxicity and Pharmacokinetic Resistance to Anti-Cancer Agents: A Review on the Pharmacogenomics Aspect.

The inter-individual differences in cancer susceptibility are somehow correlated with the genetic differences that are caused by the polymorphisms. These genetic variations in drug-metabolizing enzymes/drug-inactivating enzymes may negatively or positively affect the pharmacokinetic profile of chemotherapeutic agents that eventually lead to pharmacokinetic resistance and toxicity against anti-cancer drugs. For instance, the CYP1B1*3 allele is associated with CYP1B1 overexpression and consequent resistance to a variety of taxanes and platins, while 496T>G is associated with lower levels of dihydropyrimidine dehydrogenase, which results in severe toxicities related to 5-fluorouracil. In this context, a pharmacogenomics approach can be applied to ascertain the role of the genetic make-up in a person's response to any drug. This approach collectively utilizes pharmacology and genomics to develop effective and safe medications that are devoid of resistance problems. In addition, recently reported genomics studies revealed the impact of many single nucleotide polymorphisms in tumors. These studies emphasized the importance of single nucleotide polymorphisms in drug-metabolizing enzymes on the effect of anti-tumor drugs. In this review, we discuss the pharmacogenomics aspect of polymorphisms in detail to provide an insight into the genetic manipulations in drug-metabolizing enzymes that are responsible for pharmacokinetic resistance or toxicity against well-known anti-cancer drugs. Special emphasis is placed on different deleterious single nucleotide polymorphisms and their effect on pharmacokinetic resistance. The information provided in this report may be beneficial to researchers, especially those who are working in the field of biotechnology and human genetics, in rationally manipulating the genetic information of patients with cancer who are undergoing chemotherapy to avoid the problem of pharmacokinetic resistance/toxicity associated with drug-metabolizing enzymes.

Does dihydropyrimidine dehydrogenase level modify plasma antioxidant capacity in colorectal cancer patients treated with fluoropyrimidines?

Colorectal cancer is the third most common cancer type worldwide. Fluoropyrimidines and their prodrug-based regimens are widely applied as primary medications. The main enzyme responsible for the rate-limiting step in pyrimidine and for the 5-fluorouracil catabolism is dihydropyrimidine dehydrogenase (DPD). We aimed to screen DPD level and the changes of plasma antioxidant capacity of colorectal cancer patients on 5-fluorouracil regimen. Human DPD Elisa Kit based on sandwich enzyme-linked immune-sorbent assay and spectrophotometric methods (FRAP and ABTS) were used in the study. No statistically significant changes in plasma scavenging activity according to the results obtained in the ABTS system have been observed after evaluating all patients and considering DPD concentration. A decrease of the ferric reducing ability of patients' plasma taken after the administered treatment was found. The increase of DPD level is accompanied by a decrease in the p values and therefore the statistical significance of the differences increases. Based on the aforementioned observations, it could be concluded that some aspects of plasma antioxidant capacity and individuals' antioxidant status might be involved in the pathogenesis of the disease and could be altered by the activity of some enzymes. The cancer therapy in question, by the specificity of its mechanism of action, can modify patient's oxidative status.

Hypoxia Drives Dihydropyrimidine Dehydrogenase Expression in Macrophages and Confers Chemoresistance in Colorectal Cancer.

Colorectal adenocarcinoma is a leading cause of death worldwide, and immune infiltration in colorectal tumors has been recognized recently as an important pathophysiologic event. In this context, tumor-associated macrophages (TAM) have been related to chemoresistance to 5-fluorouracil (5-FU), the first-line chemotherapeutic agent used in treating colorectal cancers. Nevertheless, the details of this chemoresistance mechanism are still poorly elucidated. In the current study, we report that macrophages specifically overexpress dihydropyrimidine dehydrogenase (DPD) in hypoxia, leading to macrophage-induced chemoresistance to 5-FU via inactivation of the drug. Hypoxia-induced macrophage DPD expression was controlled by HIF2α. TAMs constituted the main contributors to DPD activity in human colorectal primary or secondary tumors, while cancer cells did not express significant levels of DPD. In addition, contrary to humans, macrophages in mice do not express DPD. Together, these findings shed light on the role of TAMs in promoting chemoresistance in colorectal cancers and identify potential new therapeutic targets. SIGNIFICANCE: Hypoxia induces HIF2α-mediated overexpression of dihydropyrimidine dehydrogenase in TAMs, leading to chemoresistance to 5-FU in colon cancers.

Dihydropyrimidine dehydrogenase level and the redox status in patients with colorectal cancer are prognostic for adverse effects of fluoropyrimidines

Drug resistance and toxicity are the most widespread limitations in the pursuit of sufficient antitumor effectiveness and successful control of oncological diseases, including colorectal cancer (CRC). Herein the objective was to investigate some hematological side effects of the chemotherapeutic regimen FOLFOX-4, their relation to dihydropyrimidine dehydrogenase (DPD) levels and the associated alterations in CRC patients’ plasma free-radical scavenging properties and extent of oxidative molecular damage. Thirty-eight patients with histologically confirmed CRC diagnoses, assigned to chemotherapy with the FOLFOX-4 regimen, were recruited. The diagnostic methods included a complete physical examination, blood routine test and general biochemistry. The DPD levels were assayed. The patients’ plasma free-radical scavenging properties and extent of molecular oxidative damage were determined by spectrophotometry and enhanced chemiluminescence. The clinico-pathological and demographics characteristics of the patients were in agreement with the reports from retrospective cohort studies. The FOLFOX-4 regimen induced a decrease in plasma free-radical scavenging properties and increased extent of lipid peroxidation. White blood cells, granulocytes and lymphocytes decreased significantly after the first cycle of the therapy. The patients’ DPD level decreased statistically significantly in the case of severe reduction (more than 25%) of white blood cells and granulocyte counts. The obtained data are in agreement with already known facts concerning the side effects of the FOLFOX-4 regimen and associated changes in redox homeostasis. Genetic predisposition to effectively metabolize and tolerate the applied therapy, i.e. DPD levels, could modulate some aspects of the observed changes in the aforementioned parameters.

Human equilibrative nucleoside transporter‐1 expression is a predictor in patients with resected pancreatic cancer treated with adjuvant S‐1 chemotherapy

The high expression of human equilibrative nucleoside transporter‐1 (hENT1) and the low expression of dihydropyrimidine dehydrogenase (DPD) are reported to predict a favorable prognosis in patients treated with gemcitabine (GEM) and 5‐fluorouracil (5FU) as the adjuvant setting, respectively. The expression of hENT1 and DPD were analyzed in patients registered in the JASPAC 01 trial, which showed a better survival of S‐1 over GEM as adjuvant chemotherapy after resection for pancreatic cancer, and their possible roles for predicting treatment outcomes and selecting a chemotherapeutic agent were investigated. Intensity of hENT1 and DPD expression was categorized into no, weak, moderate or strong by immunohistochemistry staining, and the patients were classified into high (strong/moderate) and low (no/weak) groups. Specimens were available for 326 of 377 (86.5%) patients. High expression of hENT1 and DPD was detected in 100 (30.7%) and 63 (19.3%) of 326 patients, respectively. In the S‐1 arm, the median overall survival (OS) with low hENT1, 58.0 months, was significantly better than that with high hENT1, 30.9 months (hazard ratio 1.75, P = 0.007). In contrast, there were no significant differences in OS between DPD low and high groups in the S‐1 arm and neither the expression levels of hENT1 nor DPD revealed a relationship with treatment outcomes in the GEM arm. The present study did not show that the DPD and hENT1 are useful biomarkers for choosing S‐1 or GEM as adjuvant chemotherapy. However, hENT1 expression is a significant prognostic factor for survival in the S‐1 arm.

593P - Dihydropyrimidine dehydrogenase (DPD) determination prior the administration of medicines containing fluorouracil: A single Spanish hospital experience

BackgroundSevere toxicity as a result of Fluoropyrimidine treatments appears in up 30% of patients. The reduce activity of DPD is one of the main cause of severe adverse events. Up to 8% of the population have low levels of DPD, and up to 0.5% of the population completely lack the enzyme. We assessed the effect of prospective screening for the 4 most relevant variants (DPYD*2A [rs3918290, c.1905+1G>A, IVS14+1G>A], c.2846A>T [rs67376798, D949V], c.1679T>G [rs55886062, DPYD*13, I560S], c.1236G>A [rs56038477, E412E, in haplotype B3]) and rs34743033 TYMS, on patient safety and dose individualization in daily clinical practice. MethodsWe described our experience in a Tertiary University Hospital. We reviewed 208 patients with gastrointestinal cancer who were planned to receive fluoropyrimide treatment and we did prospective genotyping for DPYD*2A, c.2846A>T, c.1679T>G, c.1236G>A and rs34743033 TYMS. Heterozygous DPD variant allele carriers received an initial dose reduction of 25% (c.2846A>T and c.1236G>A) or 50% (DPYD*2A and c.1679T>G), and DPYD wild-type patients were treated according to the current standard of care. ResultsFrom April 2017 to March 2019, 208 patients were pre-tested. 8 patients (3´8%) were heterozygous DPD variant allele carriers and 200 (96´2%) were DPD wild-type patients. Overall, fluoropyrimidine-related severe toxicity was higher in DPD variant carriers (2 [25%] of 8 patients) than in wild-type patients (70 [35%] of 200 patients). 2 patients with c.1236G>A and rs34743033 TYMS heterozygous were necessary to disrupt treatment in spite of dose reduction because of severe diarrhea. However, the other 6 heterozygous have low grade toxicity with reduction preplanned. ConclusionsLife-threatening toxicities could be presented in patients with DPD deficiency if they are treated with standar dose of fluoropyridimes. Last colorectal cancer ESMO guidelines do not recommend testing DPD deficient up front. It recommend in case of patients who experience severe toxicity, DPD levels should be tested before 5-FU is re-introduced. We suggest due to our control of potential toxicities that implementation of DPD genotype individualised dosing should be a new standard of care.Legal entity responsible for the study: Mediano Rambla. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.

Dihydropyrimidine Dehydrogenase Levels in Colorectal Cancer Cells Treated with a Combination of Heat Shock Protein 90 Inhibitor and Oxaliplatin or Capecitabine.

Purpose: Dihydropyrimidine dehydrogenase (DPD) is the principal enzyme in the catabolism of fluoropyrimidine drugs including capecitabine. A recent report has suggested that oxaliplatin chemotherapy is associated with elevated DPD levels and chemoresistance pattern. As a newly developed chemotherapeutic agent, 17-allyloamino-17-demethoxy-geldanamycin (17-AAG) can be effective in combination therapy with oxaliplatin and capecitabine in colorectal cancer (CRC). DPD expression level can be a predictive factor in oxaliplatin and capecitabine-based chemotherapy. We evaluated DPD in mRNA and protein levels with new treatments: 17-AAG in combination with oxaliplatin and capecitabine in HT-29 and HCT-116 cell lines. Methods: Drug sensitivity was determined by the water-soluble tetrazolium-1 assay in a previous survey. Then, we evaluated the expression levels of DPD and its relationship with the chemotherapy response in capecitabine, oxaliplatin, and 17-AAG treated cases in single and combination cases in two panels of CRC cell lines. DPD gene and protein expression levels were determined by real-time polymerase chain reaction and western blotting assay, respectively. Results: DPD gene expression levels insignificantly increased in single-treated cases versus untreated controls in both cell lines versus controls. Then, the capecitabine and oxaliplatin were added in double combinations, where DPD gene and protein expression increased in combination cases compared to pre-chemotherapy and single drug treatments. Conclusion: The elevated levels of cytotoxicity in more effective combinations could be related to a different mechanism apart from DPD mediating effects or high DPD level in the remaining resistance cells (drug-insensitive cells), which should be investigated in subsequent studies.

5-Fluorouracil-based adjuvant chemotherapy improves the clinical outcomes of patients with lymphovascular invasion of upper urinary tract cancer and low expression of dihydropyrimidine dehydrogenase.

Lymphovascular invasion (LVI) by urothelial carcinoma of the upper urinary tract (UC-UUT) is associated with an unfavorable prognosis. However, a high proportion of patients with UC-UUT are unable to receive the recommended doses of cisplatin-based adjuvant chemotherapy due to advanced age or renal dysfunction resulting from nephroureterectomy. Tegafur-uracil is an oral form of 5-fluorouracil whose efficacy is influenced by the activities of enzymes associated with its metabolism, such as dihydropyrimidine dehydrogenase (DPD), orotatephosphoribosyltransferase (OPRT) and thymidylate synthase (TS). The aim of the present study was to investigate the efficacy of adjuvant 5-fluorouracil chemotherapy for UC-UUT with LVI, and to assess the expression of enzymes associated with 5-fluorouracil metabolism as promising biomarkers of therapy efficacy. The present study retrospectively investigated 52 cases of UC-UUT. Following nephroureterectomy, tegafur-uracil was administered to 15 out of 30 patients with LVI who were not eligible for cisplatin-based adjuvant chemotherapy. Levels of DPD, OPRT and TS expression in tumor specimens were determined by reverse transcription-quantitative polymerase chain reaction, and their associations with the efficacy of adjuvant 5-fluorouracil chemotherapy were analyzed. The levels of DPD, OPRT and TS expression were not associated with pathological factors or outcome, although a higher expression of TS was associated with a poorer outcome. Adjuvant 5-fluorouracil chemotherapy significantly improved the outcome of patients with lower DPD expression. However, the levels of OPRT and TS expression did not influence therapeutic efficacy. Adjuvant 5-fluorouracil chemotherapy appears to be effective for lymphovascular-invasive UC-UUT in patients with lower DPD expression.

Thymidine phosphorylase affects clinical outcome following surgery and mRNA expression levels of four key enzymes for 5‑fluorouracil metabolism in patients with stage�I and II non‑small cell lung cancer

The expression levels of thymidine phosphorylase (TP), dihydropyrimidine dehydrogenase (DPD), thymidylate synthase (TS) and orotate phosphoribosyltransferase (OPRT) may predict the clinical efficacy of 5-fluorouracil-based chemotherapy in patients with cancer. We herein investigated the differences in the mRNA levels of these enzymes in non-small-cell lung cancer (NSCLC) and evaluated their prognostic value for NSCLC treated by surgical resection. The intratumoral mRNA levels of TP, DPD, TS, and OPRT were quantified in 66 patients with pathological stage I and II NSCLC (adenocarcinoma or squamous cell carcinoma) following complete resection according to the Danenberg Tumor Profile method. The TP level was the only significant prognostic factor for disease-specific survival (DSS) following complete resection; the mean TP mRNA level differed significantly between the high and low mRNA expression groups. The DSS at 5 years was significantly higher in the low TP mRNA compared with that in the high TP mRNA expression group (83.4 vs. 58.6%, respectively; P=0.005). A Cox proportional hazards model revealed that pathological stage, sex, and TP expression were independent prognostic factors for DSS in patients with stage I and II NSCLC following complete resection. Thus, TP level may be used to monitor treatment efficacy and predict the outcome of NSCLC patients.

Measurement of Nucleic Acid Metabolizing Enzymes in Stage III Colorectal Cancer Adds Precision to Adjuvant Fluorouracil and Leucovorin Therapy

1. Abstract 1.1. <span style=font-size:10.0pt;mso-fareast-font-family: ms= mincho=>Background <span style=font-size:10.0pt;mso-fareast-font-family: ms= mincho=>: Recurrence of colorectal cancer has been shown to be inhibited by adjuvant chemotherapy. To achieve effective adjuvant chemotherapy, a target molecule is necessary . Therefore, we performed a prospective clinical trial to determine the relationship between adjuvant chemotherapy outcomes and prognostic factors in colorectal cancer based on nucleic acid metabolizing enzyme levels. 1.2. Methods: A total of 147 patients with stage IIIA, IIIB, and IIIC cancer were selected for adjuvant chemotherapy. We analyzed Disease-Free Survival (DFS) as the primary endpoint and Overall Survival (OS) as the secondary endpoint in relation to the Thymidylate Synthase (TS) and Dihydropyrimidine Dehydrogenase (DPD) levels as measured by enzyme-linked immunosorbent assay. According <span style=letter-spacing: -.15pt>to the levels of the mean preliminary TS of 21.0 ng/mg protein and DPD of 115 ng/mg protein, the patients were divided into 4 groups. They were then administered postoperative adjuvant chemotherapy that primarily included fluorouracil and Leucovorin (FL) or Uracil/Tegafur (UFT) and Leucovorin (UZEL) for 6 months. 1.3. Results: The 5-year DFS in advanced stage III cancer was 63.9%. A significant difference was observed between the LL (low TS and low DPD levels) and HL (high TS and low DPD levels) groups and the LH (low TS and high DPD levels) and HH (high TS and high DPD levels) groups. Multivariate<span style=letter-spacing: -.5pt> analysis revealed a significant difference<span style=letter-spacing: -.1pt> in stage, TS level, and TS and DPD levels. The OS was 79.6% for all the groups. A significant difference was observed between the LL, LH, and HL groups and the HH groups. Multivariate analysis revealed a significant difference<span style=letter-spacing: -.5pt> in the stage, age, TS level, and<span style=letter-spacing: -.55pt> TS and DPD levels. <span style=font-size:10.0pt;letter-spacing: -.15pt>1.4. Conclusions: Measurement of the TS and DPD levels of a primary colorectal cancer lesion as target molecules may be helpful for achieving an effective postoperative adjuvant chemotherapy. TS and DPD can potentially serve as more accurate predictors of OS than age and cancer stage. 2. Keywords: Adjuvant Chemotherapy; Colorectal Cancer; Metabolizing <span style=font-size: 10.0pt;mso-fareast-font-family: ms= mincho=> <span style=font-size: 10.0pt>Enzyme; Precision Medicine

Pharmacokinetics of continuous transarterial infusion of 5-fluorouracil in patients with advanced hepatocellular carcinoma.

Numerous studies concerning hepatic arterial infusion chemotherapy (HAIC) have been conducted by adopting regimens containing 5-fluorouracil (FU), with a favourable efficacy compared with conventional transcatheter arterial chemoembolisation (TACE) treatment; however, the detailed mechanism of HAIC remains unclear. The present study aimed to evaluate peripheral concentration time curves of 5-FU administered through the hepatic artery, which may additionally explain the mechanism of action of HAIC. A total of 10 eligible patients underwent transcatheter arterial embolization and a 2-day HAIC treatment regimen using a folinic acid, fluorouracil and oxaliplatin regimen. Peripheral venous blood sampling was performed in each patient prior to infusion, and at 0, 0.5, 1, 1.5, 2, 5, 10, 15, 22 and 23 h following the start of infusion. The blood sample at 0 h was analysed for dihydropyrimidine dehydrogenase (DPD) levels by high performance liquid chromatography, and the rest of the samples were analysed for 5-FU by optimised liquid chromatography-mass spectrometry (LC-MS). The lower limit of quantification of optimised LC-MS for 5-FU was 5 ng/ml. The steady-state plasma concentration of 5-FU administered through the hepatic artery was achieved after 15 h. This concentration largely varied, ranging from 8.64–152.00 ng/ml. Optimised LC-MS may detect low concentrations of 5-FU. The steady-state concentration of 5-FU administered through the hepatic artery was achieved after 15 h. DPD levels were analysed through determining the ratio of plasma uracil (U) and dihydrouracil (UH2) by HPLC, and the results indicated a mild DPD deficiency in the patients with HCC. These results may provide a basis for the explanation of the clinical efficacy of HAIC, and to additionally optimise its efficacy.

Elevated levels of mRNAs encoding dihydropyrimidine dehydrogenase and thymidylate synthase are associated with improved survival of patients with hepatocellular carcinoma treated with S-1.

Thymidylate synthase (TYMS) and dihydropyrimidine dehydrogenase (DPYD) are associated with the response of tumors to fluoropyrimidines. The aim of the present study was to investigate the association between the levels of TYMS and DPYD mRNAs and the efficacy of S-1 for treating patients with HCC. A total of 35 patients with HCC who received S-1 upon recurrence (S-1 group) and 20 patients who never received a fluoropyrimidine (control group) were studied. The levels of TYMS and DPYD mRNA in surgically resected specimens were determined using reverse transcription-polymerase chain reaction assays. Overall survival (OS) time of S-1 group patients with high levels of DPYD mRNA was significantly longer compared with that of patients with low levels (median 501 days vs. 225 days; P=0.016). Similarly, the OS time of those patients with high levels of TYMS mRNA was significantly longer compared with those with low levels (median 503 days vs. 239 days; P=0.0076). By contrast, there was no difference in OS time of the control group between patients with high and low levels of DPYD and TYMS mRNAs. The levels of TYMS and DPYD mRNAs may serve as predictive markers for patients with HCC who receive S-1 chemotherapy.

Higher Tissue Levels of Thymidylate Synthase Determined by ELISA Are Associated with Poor Prognosis of Patients with Lung Cancer.

Thymidylate synthase (TS) is essential in thymidylate biosynthesis and DNA replication. Dihydropyrimidine dehydrogenase (DPD) is a rate-limiting enzyme in pyrimidine catabolism and is important in catabolism of 5-fluorouracil (5-FU). The significance of TS and DPD expressed in lung cancer remains controversial. Here we analyzed the relationship between TS and DPD expression and clinicopathological features of lung cancer. Enzyme-linked immunosorbent assays (ELISAs) were used to measure TS and DPD levels in paired tumor and non-tumor lung tissues obtained from 168 patients (107 adenocarcinomas, 39 squamous cell carcinomas, and 22 others), who had operations at the Shinshu University Hospital from 2004 to 2007 and were followed up for a median of 57.0 months. TS and DPD expression levels were higher in tumor tissues, and TS expression levels were significantly lower in adenocarcinomas than those in other subtypes. In addition, patients with low TS levels survived longer compared with patents with high TS levels. By contrast, DPD expression levels were not correlated with overall patient survival. Importantly, patients with low TS and DPD levels exhibited significantly prolonged survival than those with high TS and DPD. Among the 168 patients, 59 patients were treated with tegafur-uracil (UFT), a DPD-inhibitory fluoropyrimidine, and the UFT-treated patients with high TS and high DPD levels showed worst prognosis. Our study demonstrates a significant correlation between low TS expression levels and long-term prognosis of patients with lung cancer. Thus, ELISA is a clinically useful method to measure TS and DPD expression in lung cancer tissues.

The Impact of the Expression Level of Intratumoral Dihydropyrimidine Dehydrogenase on Chemotherapy Sensitivity and Survival of Patients in Gastric Cancer: A Meta-Analysis.

The potential impact that the intratumoral expression level of dihydropyrimidine dehydrogenase (DPD) has on chemotherapy sensitivity and long-term survival for gastric cancer (GC) patients remains controversial; therefore, this study seeks to clarify this issue. Our meta-analysis was performed using Review Manager (RevMan) 5.3 software. In vitro drug sensitivity tests, correlation coefficients between sensitivity to 5-fluorouracil (5-FU), and expression levels of intratumoral DPD were used as effective indexes to analyse. Overall survival (OS) and progression-free survival (PFS) were used as endpoints for patient outcome, and hazard ratios (HRs) and 95% confidence intervals (CIs) were noted as measures of effect. There were 15 eligible studies including 1805 patients for the final analysis. The analysis revealed a statistically significant difference between the expression level of intratumoral DPD activity, DPD mRNA levels, and sensitivity to 5-FU in GC patients, with high expression levels of intratumoral DPD resulting in low sensitivity to 5-FU. However, no matter what therapeutic regimens were used, there was no significant difference for patient outcomes between high and low DPD expression groups, either in OS or in PFS. In conclusion, high levels of intratumoral DPD expression have a negative impact on sensitivity to 5-FU in GC patients, but no prognostic value for long-term survival was uncovered.

Suppression of TWIST1 enhances the sensitivity of colon cancer cells to 5-fluorouracil

The 5-fluorouracil (5FU)-based adjuvant chemotherapy improves the survival of patients with colorectal cancer, however the main obstacle affecting its effectiveness is a drug resistance. Our study aimed to investigate the impact of TWIST1 silencing on the sensitivity of cancer cells to 5FU. The suppression of TWIST1 expression in human colon cancer HT29 and HCT116 cell lines was achieved by transduction with lentiviral vector carrying the TWIST1 silencing sequence (pLL3.7-shTWIST1). The suppression of TWIST1 expression induced changes in the expression pattern of epithelial to mesenchymal transition markers, reduced the cells proliferation rate, increased their sensitivity to serum withdrawn, and increased the cytotoxic effect of 5FU. However, significantly higher 5FU cytotoxicity was observed in HT29 cell cultures. Cells with silenced TWIST1 displayed altered expression of enzymes metabolizing 5FU. The expression level of dihydropyrimidine dehydrogenase, and thymidylate synthase decreased significantly in HT29 shTWIST1 cells, but not in HCT116 shTWIST1 cells. On the other hand, significant increases in the expression levels of thymidine phosphorylase, and uridine phosphorylase 1 were seen in both cell lines with suppressed expression of TWIST1. The changes in enzymes expression were mirrored by enzymatic activities. In conclusion, our observations point to TWIST1 as a target protein to enhance the sensitivity of colorectal cancer cells to 5FU.

Abstract 5028: Reverse translational research for identifying the correlation between EGFR mutation status and DPD protein expression in lung adenocarcinoma

Abstract [Background] Reverse translation research is often described as “From the Bedside to the Bench”, which means taking an understanding gained by observations in a patient population to create hypotheses and confirmation of the hypothesis in the laboratory. According to current chemotherapy treatment for lung adenocarcinoma, empirically, clinicians know that epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR-TKI) tend to be effective for radiological ground glass nodule- type lung adenocarcinomas. On the other hand, it has been shown that 5-FU sensitivity in patients with non-small cell lung cancer (NSCLC) is associated with EGFR mutation status. From such clinical hints, we identified a relationship between dihydropyrimidine dehydrogenase (DPD), a 5-FU degrading enzyme, and EGFR mutation status. [Methods] We firstly focused on clinicopathologic factors and in vitro correlations between DPD expression and EGFR mutation status. Secondly, we analyzed crosstalk between the EGFR signal cascade and DPD protein expression using EGFR mutated and not mutated cell lines. [Clinicopathological Study] EGFR mutations and messenger RNA (mRNA) levels of DPD were analyzed in 47 resected NSCLC tumors by laser-capture microdissection. EGFR mutation status and the immunohistochemical expression of DPD in 49 resected NSCLC tumors were also examined. As a result, adenocarcinoma in situ showed significantly higher DPD mRNA levels and more EGFR mutation frequency than other histological types (P &amp;lt; 0.05). DPD immunopositive cases were more frequently observed in adenocarcinoma, in females, and in nonsmokers; which were correlated with EGFR mutation status (P &amp;lt; 0.003). [Basic Study] In vitro, EGFR-mutated cell lines (PC9, HCC827; exon19 E746-A750 and H1975; exon21 L858R, T790M, gefitinib resistant) showed higher DPD mRNA and protein expression than wild types (H1437, H1299). The DPD gene (DPYD), and DPD protein expression were known to be regulated by the transcription factor Sp1. In the PC9 study, EGF treatment induced up-regulation of both Sp1 and DPD. Gefitinib, an EGFR-TKI, and mithramycin A, specific Sp-1 inhibitors, suppressed them. However, the phenomena were not observed in EGFR-wild types and EGFR-TKI resistant cell lines. These results suggest DPD is regulated mainly in EGFR signal cascade enhanced lung cancers such as EGFR mutated adenocarcinomas. 5-FU and its derivatives such as uracil-tegafur (UFT) or S-1 might be effective for EGFR wild type adenocarcinomas because of the low DPD expression. [Conclusion] Reverse translational research can provide useful information for clinical treatment. In the present study, we identified crosstalk between the EGFR signal cascade and DPD protein expression, which might affect therapeutic strategy for lung adenocarcinomas. Citation Format: Tomoshi Tsuchiya, Tetsuo Tominaga, Koji Mochinaga, Naoya Yamasaki, Keitaro Matsumoto, Takuro Miyazaki, Go Hatachi, Yuka Kitajima, Takeshi Nagayasu. Reverse translational research for identifying the correlation between EGFR mutation status and DPD protein expression in lung adenocarcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5028.

Abstract 2159: In vitro characterization of PTAU and FU interactions in colon cancer cells

Abstract Background: Fluorouracil (FU) remains a main anticancer therapy for colorectal cancer (CRC) and other solid tumors. The mechanism of action of FU is associated with inhibition of thymidylate synthase (TS) and incorporation of its metabolites into RNA and DNA. High toxicity and wide-spread chemoresistance, however, have limited the utilization of FU-based therapies. Five intracellular enzymes, thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), methylenetetrahydrofolate reductase (MTHFR), thymidine phosphorylase (TP), and uridine phosphorylase (UP) are key determinants of FU sensitivity or resistance. Combination therapies aimed at improving the bioavailability of FU and reducing host toxicity has been evaluated. Recently, our group developed a new uridine phosphorylase inhibitor, 5-phenylthio-acyclouridine (PTAU) that has shown promise in reducing host toxicity and increasing FU efficacy in vivo. The current studies were to characterize interactions of PTAU and FU in vitro and to assess its effects on key metabolic enzymes in human colon cancer cells. Hypothesis: We hypothesized that inhibition of uridine phosphorylase by PTAU would ameliorate the toxic effects of FU and enhance its efficacy by permitting increased doses of FU. Methods: Three colon cancer cell lines with differing p53 status, HCT116-p53wt (wild-type), HCT116-p53null, and HT-29 (p53-mutant); and a normal colonic epithelial cell line, CRL-1790, were used. Doubling times were determined, and IC50 values for FU were derived from kill curves using MTT assay. Cells were treated for 72 hours with IC50 doses of FU, PTAU (100 μM) or uridine (25 μM), alone or in combination, or with the solvent, DMSO. mRNA levels for DPD, TS, TP, and UP were quantitated by qRT-PCR; for intracellular protein expression, cells were fixed and stained with monoclonal antibodies and analyzed by flow cytometry. Results: FU sensitivity correlated with cell doubling times. Basal expression of FU metabolic enzymes differed between CRC and normal cells. mRNAs for DPD and UP were higher in normal relative to cancer cells, but TS mRNA was higher in cancer cells. FU treatment upregulated mRNA expression of DPD, UP, and TS in cancer cells but not in normal cells. Only in cancer cells, DPD induction by FU was potentiated by PTAU. In contrast, treatment with FU decreased protein levels of DPD, TP, and TS in cancer cells. PTAU induced TS protein expression in cancer cells, an effect that was reduced by co-treatment with FU. Conclusions: FU induces mRNA levels of DPD, UP, and TS in cancer cell lines, but protein levels are reduced; the discrepancy between mRNA and protein levels following FU treatment underscores the need for evaluation of colon cancer samples to assess response to FU therapy. This work was supported by a Supplement of the MSM/TU/UABCCC U54 Partnership grant (3U54-CA118948-09S1) from NIH. Citation Format: Esther A. Suswam, Gaurav Kumar, Hyung-Gyoon Kim, Mohamed Osmar, Mahmoud H. el Kouni, Upender Manne. In vitro characterization of PTAU and FU interactions in colon cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2159.

Dihydropyrimidine Dehydrogenase Is a Prognostic Marker for Mesenchymal Stem Cell-Mediated Cytosine Deaminase Gene and 5-Fluorocytosine Prodrug Therapy for the Treatment of Recurrent Gliomas.

We investigated a therapeutic strategy for recurrent malignant gliomas using mesenchymal stem cells (MSC), expressing cytosine deaminase (CD), and prodrug 5-Fluorocytosine (5-FC) as a more specific and less toxic option. MSCs are emerging as a novel cell therapeutic agent with a cancer-targeting property, and CD is considered a promising enzyme in cancer gene therapy which can convert non-toxic 5-FC to toxic 5-Fluorouracil (5-FU). Therefore, use of prodrug 5-FC can minimize normal cell toxicity. Analyses of microarrays revealed that targeting DNA damage and its repair is a selectable option for gliomas after the standard chemo/radio-therapy. 5-FU is the most frequently used anti-cancer drug, which induces DNA breaks. Because dihydropyrimidine dehydrogenase (DPD) was reported to be involved in 5-FU metabolism to block DNA damage, we compared the survival rate with 5-FU treatment and the level of DPD expression in 15 different glioma cell lines. DPD-deficient cells showed higher sensitivity to 5-FU, and the regulation of DPD level by either siRNA or overexpression was directly related to the 5-FU sensitivity. For MSC/CD with 5-FC therapy, DPD-deficient cells such as U87MG, GBM28, and GBM37 showed higher sensitivity compared to DPD-high U373 cells. Effective inhibition of tumor growth was also observed in an orthotopic mouse model using DPD- deficient U87MG, indicating that DPD gene expression is indeed closely related to the efficacy of MSC/CD-mediated 5-FC therapy. Our results suggested that DPD can be used as a biomarker for selecting glioma patients who may possibly benefit from this therapy.

In Vivo Antitumor Activity of Folate-Conjugated Cholic Acid-Polyethylenimine Micelles for the Codelivery of Doxorubicin and siRNA to Colorectal Adenocarcinomas.

Multidrug resistance poses a great challenge to cancer treatment. In order to improve the targeting and codelivery of small interfering RNA (siRNA) and doxorubicin, and to overcome multidrug resistance, we conjugated a cholic acid-polyethylenimine polymer with folic acid, forming CA-PEI-FA micelles. CA-PEI-FA exhibited a low critical micelle concentration (80 μM), small average particle size (150 nm), and positive zeta potential (+ 12 mV). They showed high entrapment efficiency for doxorubicin (61.2 ± 1.7%, w/w), forming D-CA-PEI-FA, and for siRNA, forming D-CA-PEI-FA-S. X-ray photoelectron spectroscopic analysis revealed the presence of external FA on D-CA-PEI-FA micelles. About 25% doxorubicin was released within 24 h at pH 7.4, while more than 30% release was observed at pH 5. The presence of FA enhanced micelle antitumor activity. The D-CA-PEI-FA and D-CA-PEI-FA-S micelles inhibited tumor growth in vivo. No significant differences between their in vitro cytotoxic activities or their in vivo antitumor effects were observed, indicating that the siRNA coloading did not significantly increase the antitumor activity. Histological analysis revealed that tumor tissues from mice treated with D-CA-PEI-FA or D-CA-PEI-FA-S showed the lowest cancer cell density and the highest levels of apoptosis and necrosis. Similarly, the livers of these mice exhibited the lowest level of dihydropyrimidine dehydrogenase among all treated groups. The lowest serum vascular endothelial growth factor level (VEGF) (24.4 pg/mL) was observed in mice treated with D-CA-PEI-FA-S micelles using siRNA targeting VEGF. These findings indicated that the developed CA-PEI-FA nanoconjugate has the potential to achieve targeted codelivery of drugs and siRNA.